Plug-in Hybrid Powertrain for Automotive Vehicles

ABSTRACT

A plug-in hybrid powertrain for automotive vehicle is provided which has an internal combustion engine; an electric machine; multiple planetary gear sets, multiple selectively engageable clutch mechanisms and an output member. Selectively engaging those clutches will achieve multiple operation modes including multiple torque transfer ratio from electric machine to output member; multiple torque transfer ratio from internal combustion engine to output member; electric machine propulsion mode; internal combustion engine propulsion mode; generator assistant vehicle launch modes for forward and reverse in the internal combustion engine vehicle launch operations; motor assistant propulsion when in internal combustion engine vehicle propulsion operations; and engine cranking mode. The plug-in hybrid powertrain achieves more torque transfer ratios and operational mode with given number of planetary gear sets and clutches then any existing system.

RELATED APPLICATION

this is the non-provisional patent application of the provisional patent application with application Number of 63/241,643 and title of Plug-in Hybrid Powertrain for Automotive Vehicles.

FIELD OF THE INVENTION

This invention relates to a plug-in hybrid powertrain for automotive vehicles.

BACKGROUND

Typical plug-in hybrid powertrains have an internal combustion engine which converts fuel to propulsion power, and one or two electrical machines (motor/generator) which converts electricity stored in a rechargeable battery to propulsion power. The propulsion powers from those power sources are delivered to vehicle axle through a power transfer system. The power transfer system has an output member which usually connects to vehicle axle through a final drive unit. The designs of such power transfer system determine the features, performance, compactness, and cost of the plug-in hybrid powertrain.

To minimize the cost of the system, this invention aimed at the plug-in hybrid powertrain with just one electrical machine along with one internal combustion engine, specifically aimed at the design of the power transfer system for so called single electrical machine plug-in hybrid powertrain. Such power transfer systems usually consist of multiple planetary gear sets and multiple selectively engageable clutches. Selectively engaging those clutches will achieve multiple operation modes including multiple torque transfer ratio from electric machine to output member; multiple torque transfer ratio from internal combustion engine to output member; electric machine propulsion mode; internal combustion engine propulsion mode; generator assistant launch modes for forward and reverse in internal combustion engine vehicle launch operations; motor assistant propulsion when in internal combustion engine vehicle propulsion operations; and engine cranking mode. One important aim of this invention is to achieve more torque transfer ratios and operation modes with given contents (given number of planetary gear sets and given number of clutches).

The desired features of a well-designed power transfer systems for the plug-in hybrid powertrains are list as the following.

-   -   1. Have suitable multiple mechanical torque transfer ratios from         the electric machine to the output element for electrical         machine propulsion operations.     -   2. Have suitable multiple mechanical torque transfer ratios from         the internal combustion engine to the output element for         internal combustion engine propulsion operations.     -   3. Have generator assistant (GA) vehicle launch modes for both         forward and reverse for launching the vehicle with internal         combustion power only. This will eliminate the traditional         vehicle launch means such as torque converter or frictional         launch clutch. That is the internal combustion engine vehicle         launch operations do not use the traditional vehicle launch         means such as torque converter or frictional launch clutch,         instead use the electrical machine in generation mode to launch         the vehicle, namely generator assistant (GA) launch. Therefore,         do not consume electrical energy.     -   4. Can propel the vehicle with summation of internal combustion         engine power and electric machine power. Especially when in         internal combustion engine propulsion operation mode, the         electric machine can add power to the propulsion, namely motor         assistant (MA) propulsion.     -   5. Can switch between electric machine drive and internal         combustion engine drive smoothly.     -   6. Can do regenerative vehicle braking.     -   7. Can recharge battery with internal combustion engine.

Various single electric machine plug-in hybrid powertrain systems have been proposed. However, none of them provides all features listed above. Some of them do not have all suitable mechanical transfer ratios for both internal combustion engine and electric machine. Some of them rely on the traditional vehicle launch mythology such as torque converter or frictional launch clutch in internal combustion engine vehicle launch operations. The aim of this invention is at power transfer systems for single electric motor plug-in hybrid powertrain, which has all above listed features, and is realized with simplest design, or could be stated as achieve more torque transfer ratios and operation modes with given number of planetary gear sets and given number of clutches.

BRIEF SUMMARY OF THE INVENTION

To better describe the invention, some basic terms are defined here first.

-   -   1. As well known by the industry, a planetary gear set (also         called differential gear set) is a gear system which has three         interrelated rotating elements. Those elements are ring gear,         planetary gear carrier and sun gear, and will be called the         first element, second element and third element in the following         descriptions.     -   2. The team ‘fixed connection’ between two elements means a         mechanical connection between the two elements which couples two         elements as one rotating body therefore always rotate at same         speed.     -   3. The team ‘clutch connection’ between two elements means a         selectively engageable clutch is deployed between the two         elements such that, when the clutch is engaged the two elements         are connected into one rotating body therefore always rotate at         same speed, when the clutch is disengaged the two elements are         disconnected therefore will rotate freely from each other.     -   4. The term ‘ground’ means the case of the power transfer         system, therefore is a stationary element.

The invented power transfer systems for single electric machine plug-in hybrid powertrains consists of multiple planetary gear sets, multiple selectively engageable clutches and provide all operational features described in the paragraph

The invented power transfer systems are constructed based on the claimed connection configuration principles, and therefore achieved a greater number of torque transfer ratios and operation modes with given number of planetary gear sets and given number of clutches.

For the embodiments with two planetary gear sets, five clutches (do not include the engine disconnect clutch which is named C0 in the following embodiment descriptions) are deployed between elements of planetary gear sets, internal combustion engine, electrical machine, ground, and output element based on the claimed connection configuration principles. Those embodiments with two planetary gear sets and five clutches achieved four torque transfer ratios from internal combustion engine to output member, four torque transfer ratio from electric machine to output member, generator assistant launch modes for forward in vehicle launch operations and engine cranking mode. Therefore, it achieves all operational features described in the paragraph [04]

For the embodiments with three planetary gear sets, five clutches (do not include the engine disconnect clutch which is named C0 in the following embodiment descriptions) are deployed between elements of planetary gear sets, internal combustion engine, electrical machine, ground, and output element based on the claimed connection configuration principles. Those embodiments with three planetary gear sets and five clutches achieved seven torque transfer ratios from internal combustion engine to output member, four torque transfer ratio from electric machine to output member, generator assistant launch modes for forward and reverse in vehicle launch operations and engine cranking mode. Therefore, it achieves all operational features described in the paragraph [04] Note, the existing planetary gear automatic transmissions with same three planetary gear sets and five clutches only achieve six torque transfer ratios from internal combustion engine to output member.

For the embodiments with four planetary gear sets, five clutches (do not include the engine disconnect clutch which is named C0 in the following embodiment descriptions) are deployed between elements of planetary gear sets, internal combustion engine, electrical machine, ground, and output element based on the claimed connection configuration principles. Those embodiments with four planetary gear sets and five clutches achieved nine torque transfer ratios from internal combustion engine to output member, four torque transfer ratio from electric machine to output member, generator assistant launch modes for forward and reverse in vehicle launch operations and engine cranking mode. Therefore, it achieves all operational features described in the paragraph [04] Note, the existing planetary gear automatic transmissions with same four planetary gear sets and five clutches only achieve eight torque transfer ratios from internal combustion engine to output member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a first embodiment of the invented plug-in hybrid powertrain system with two planetary gear sets.

FIG. 2 is a schematic diagram of a second embodiment of the invented plug-in hybrid powertrain system with two planetary gear sets.

FIG. 3 is a schematic diagram of a third embodiment of the invented plug-in hybrid powertrain system with two planetary gear sets.

FIG. 4 is a schematic diagram of a fourth embodiment of the invented plug-in hybrid powertrain system with two planetary gear sets.

FIG. 5 is a schematic diagram of a fifth embodiment of the invented plug-in hybrid powertrain system with three planetary gear sets.

FIG. 6 is a schematic diagram of a sixth embodiment of the invented plug-in hybrid powertrain system with three planetary gear sets.

FIG. 7 is a schematic diagram of a seventh embodiment of the invented plug-in hybrid powertrain system with three planetary gear sets.

FIG. 8 is a schematic diagram of an eighth embodiment of the invented plug-in hybrid powertrain system with three planetary gear sets.

FIG. 9 is a schematic diagram of a nineth embodiment of the invented plug-in hybrid powertrain system with four planetary gear sets.

FIG. 10 is a schematic diagram of a tenth embodiment of the invented plug-in hybrid powertrain system with four planetary gear sets.

FIG. 11 is a schematic diagram of an eleventh embodiment of the invented plug-in hybrid powertrain system with four planetary gear sets.

FIG. 12 is a schematic diagram of a twelfth embodiment of the invented plug-in hybrid powertrain system with four planetary gear sets.

FIG. 13 is a schematic diagram of a thirteenth embodiment of the invented plug-in hybrid powertrain system with four planetary gear sets.

FIG. 14 is a schematic diagram of a fourteenth embodiment of the invented plug-in hybrid powertrain system with four planetary gear sets.

FIG. 15 is a schematic diagram of a fifteenth embodiment of the invented plug-in hybrid powertrain system with four planetary gear sets.

FIG. 16 is a schematic diagram of a sixteenth embodiment of the invented plug-in hybrid powertrain system with four planetary gear sets.

FIG. 17 is a table of clutch states of embodiments of the invented plug-in hybrid powertrain system with two planetary gear sets.

FIG. 18 is a table of clutch states of embodiments of the invented plug-in hybrid powertrain system with three planetary gear sets.

FIG. 19 is a table of clutch states of embodiments of the invented plug-in hybrid powertrain system with four planetary gear sets.

FIG. 20 is a table of clutch states of embodiments of the invented plug-in hybrid powertrain system with four planetary gear sets.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the Figures, wherein like reference numbers refer to like components throughout the several views. FIG. 1 shows a first embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of two simple planetary gear sets 10 and 20. The planetary gear set 10 has three interrelated rotation elements labeled 11, 12 and 13, and the planetary gear set 20 has three interrelated rotation elements labeled 21, 22 and 23. Fixed connections between element 12 and element 23 and output shaft 43 make them as one rotating body. The clutch C1 establishes a clutch connection between the element 11 and element 21. The clutch C2 establishes a clutch connection between element 11 and element 22. The clutch C3 establishes a clutch connection between element 13 and element 22. The clutch B1 establishes a clutch connection between element 22 and ground 31. The clutch B2 establishes a clutch connection between element 21 and ground 31. The clutch C0 establishes a clutch connection between element 11 and the internal combustion engine 41. The electric machine 42 is coupled with element 13.

The plug-in hybrid powertrain system shown in FIG. 1 can achieve multiple operation modes by selectively engage clutches. The engagement states of the clutches C0, C1, C2, C3, B1 and B2 for each operation mode are summarized in the table shown in FIG. 17 and described in the following.

The first group of operation modes is the electric machine only propulsion operation group. It includes multiple transfer ratio modes for electric machine propulsion as:

1. In the first transfer ratio mode of electric machine propulsion operation, the clutch C1 and B1 are engaged, and all other clutches are disengaged. The internal combustion engine 41 is off, and the electric machine 43 provides electric propulsion and regenerative break operation.

-   -   2. In the second transfer ratio mode of electric machine         propulsion operation, the clutch C2 and B1 are engaged, and all         other clutches are disengaged. The internal combustion engine 41         is off, and the electric machine 43 provides electric propulsion         and regenerative break operation. The second transfer ratio of         electric machine propulsion operation can be also achieved by         having clutch C1 and B2 engaged.     -   3. In the third transfer ratio mode of electric machine         propulsion operation, the clutch C2 and B2 are engaged, and all         other clutches are disengaged. The internal combustion engine 41         is off, and the electric machine 43 provides electric propulsion         and regenerative break operation.

4. In the fourth transfer ratio mode of electric machine propulsion operation, the clutch C1 and C2 are engaged, and all other clutches are disengaged. The internal combustion engine 41 is off, and the electric machine 43 provides electric propulsion and regenerative break operation.

The second group of operation modes is the internal combustion engine propulsion with electric machine power assistant operation group which includes multiple transfer ratio modes for internal combustion engine propulsion as:

-   -   1. The first transfer ratio mode of internal combustion engine         propulsion operation provides the vehicle launch operation in         which the clutch C0 and B1 are engaged, and all other clutches         are disengaged. The internal combustion engine provides         propulsion power, and the electric machine is in generation         mode, therefore no consumption of electricity. Such internal         combustion engine vehicle launch operation is called generator         assistant (GA) launch.     -   2. In the second transfer ratio mode of internal combustion         engine propulsion operation the clutch C0, C3 and B1 are         engaged, and all other clutches are disengaged. In this mode,         during the vehicle propulsion operation, the internal combustion         engine provides propulsion power, and the electric machine is         off. During the vehicle braking operation the electric machine         provides regenerative braking. In the regeneration braking         operation, the clutch C0 can be disengaged to gain more         electricity from regenerative braking.     -   3. In the third transfer ratio mode of internal combustion         engine propulsion operation the clutch C0, C3 and B2 are         engaged, and all other clutches are disengaged. In this mode,         during the vehicle propulsion operation, the internal combustion         engine provides propulsion power, and the electric machine is         off. During the vehicle braking operation the electric machine         provides regenerative braking. In the regeneration braking         operation, the clutch C0 can be disengaged to gain more         electricity from regenerative braking.     -   4. In the fourth transfer ratio mode of internal combustion         engine propulsion operation the clutch C0, C3 and C2 are         engaged, and all other clutches are disengaged. In this mode,         during the vehicle propulsion operation, the internal combustion         engine provides propulsion power, and the electric machine is         off. During the vehicle braking operation the electric machine         provides regenerative braking. In the regeneration braking         operation, the clutch C0 can be disengaged to gain more         electricity from regenerative braking.     -   5. In the fifth transfer ratio mode of internal combustion         engine propulsion operation the clutch C0, C2 and B2 are         engaged, and all other clutches are disengaged. In this mode,         during the vehicle propulsion operation, the internal combustion         engine provides propulsion power, and the electric machine is         off. During the vehicle braking operation the electric machine         provides regenerative braking. In the regeneration braking         operation, the clutch C0 can be disengaged to gain more         electricity from regenerative braking.     -   6. In the reverse transfer ratio mode of internal combustion         engine propulsion operation, the clutch C0, Cl and B1 are         engaged, and all other clutches are disengaged. In this mode,         during the vehicle propulsion operation, the internal combustion         engine provides propulsion power, and the electric machine is         off. The vehicle launch in reverse is achieved by slipping         control of one of three clutches C0, C1 or B1.     -   7. In the engine cranking mode of internal combustion engine         propulsion operation, the clutch C0 is engaged, and all other         clutches are disengaged. In this mode the electric machine         provides engine cranking torque to start the internal combustion         engine.     -   8. When in the internal combustion engine propulsion operation         modes excepting one in which the electric machine is grounded,         the electric machine can provide power assistant to maximized         vehicle propulsion power, such operation is called motor         assistant (MA) propulsion.

With this plug-in hybrid powertrain, the vehicle could be programmed to have the following three operation methods.

In the first operation method, at low vehicle speed or in city driving the electric machine only propulsion will be used. At high vehicle speed or highway driving the internal combustion engine will be started, and then internal combustion engine propulsion will be used. During the internal combustion engine propulsion, the motor assistant (MA) propulsion could be used. The internal combustion engine can be started by engaging the clutch C0 when in the second transfer ratio or above of electric machine propulsion operation.

In the second operation method, the electric machine only propulsion will be used all the time no matter low or high vehicle speed nor city or highway driving.

The third operation method will be selected if the rechargeable propulsion battery is depleted. In this operation method only internal combustion engine propulsion is used, and the vehicle launch is achieved with generator assistant (GA) method.

The regenerative braking is available in all about three operation methods.

FIG. 2 shows a second embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of two simple planetary gear sets 10 and 20. The planetary gear set 10 has three interrelated rotation elements labeled 11, 12 and 13, and the planetary gear set 20 has three interrelated rotation elements labeled 21, 22 and 23. Fixed connections between element 12 and element 21 and output shaft 43 make them as one rotating body. The clutch C1 establishes a clutch connection between the element 13 and element 23. The clutch C2 establishes a clutch connection between element 13 and element 22. The clutch C3 establishes a clutch connection between element 11 and element 22. The clutch B1 establishes a clutch connection between element 22 and ground 31. The clutch B2 establishes a clutch connection between element 23 and ground 31. The clutch C0 establishes a clutch connection between element 13 and the internal combustion engine 41. The electric machine 42 is coupled with element 11. The descriptions of operation modes of the second embodiment shown in FIG. 2 and its vehicle operation methods are identical to the first embodiment described above since the same reference numbers refer to alike components. The engagement states of the clutches C0, C1, C2, C3, B1 and B2 for each operation mode are summarized in the table shown in FIG. 17 .

FIG. 3 shows a third embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of a compound (double-pinion gear) planetary gear set 10 and a simple planetary gear set 20. The compound planetary gear set 10 has three interrelated rotation elements labeled 11, 12 and 13, and the simple planetary gear set 20 has three interrelated rotation elements labeled 21, 22 and 23. Fixed connections between element 11 and element 21 and output shaft 43 make them as one rotating body. The clutch C1 establishes a clutch connection between the element 12 and element 23. The clutch C2 establishes a clutch connection between element 12 and element 22. The clutch C3 establishes a clutch connection between element 13 and element 23. The clutch B1 establishes a clutch connection between element 22 and ground 31. The clutch B2 establishes a clutch connection between element 23 and ground 31. The clutch C0 establishes a clutch connection between element 12 and the internal combustion engine 41. The electric machine 42 is coupled with element 13. The descriptions of operation modes of the third embodiment shown in FIG. 3 and its vehicle operation methods are identical to the first embodiment described above since the same reference numbers refer to alike components. The engagement states of the clutches C0, C1, C2, C3, B1 and B2 for each operation mode are summarized in the table shown in FIG. 17 .

FIG. 4 shows a fourth embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of a compound (double-pinion gear) planetary gear set 20 and a simple planetary gear set 10. The compound planetary gear set 20 has three interrelated rotation elements labeled 21, 22 and 23, and the simple planetary gear set 10 has three interrelated rotation elements labeled 11, 12 and 13. Fixed connections between element 12 and element 23 and output shaft 43 make them as one rotating body. The clutch C1 establishes a clutch connection between the element 11 and element 22. The clutch C2 establishes a clutch connection between element 11 and element 21. The clutch C3 establishes a clutch connection between element 13 and element 22. The clutch B1 establishes a clutch connection between element 22 and ground 31. The clutch B2 establishes a clutch connection between element 21 and ground 31. The clutch C0 establishes a clutch connection between element 11 and the internal combustion engine 41. The electric machine 42 is coupled with element 13. The descriptions of operation modes of the fourth embodiment shown in FIG. 4 and its vehicle operation methods are identical to the first embodiment described above since the same reference numbers refer to alike components. The engagement states of the clutches C0, C1, C2, C3, B1 and B2 for each operation mode are summarized in the table shown in FIG. 17 .

FIG. 5 shows a fifth embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of three planetary gear sets. The first planetary gear set 10 is a simple planetary gear set, and has three elements labeled 11, 12 and 13. The second planetary gear set 20 is a simple planetary gear set, and has three elements labeled 21, 22 and 23. The third planetary gear set 50 is compound (double-pinion gear) planetary gear set, and has three elements labeled 51, 52 and 53. Elements 13 and 23 are connected with a fixed connection, and elements 21 and 53 are connected with another fixed connection, therefore there are total of two fixed connections deployed between neighboring planetary gear sets. The clutch C1 establishes a clutch connection between the element 11 and element 22. The clutch C2 establishes a clutch connection between element 23 and element 52. The clutch C3 establishes a clutch connection between element 12 and element 22. The clutch B1 establishes a clutch connection between element 11 and ground 31. The clutch B2 establishes a clutch connection between element 52 and ground 31. The clutch C0 establishes a clutch connection between element 12 and the internal combustion engine 41. The electric machine 42 is coupled with element 11, therefore the electric machine 42 is coupled with element 11 as well as with the grounding clutch B1 and connection clutch C1. The element 51 is coupled with the output shaft 43. The operation modes and vehicle operation methods of this embodiment are as same as what are described for the first embodiment of FIG. 1 , except that this embodiment has more transfer ratio for both electric machine propulsion and internal combustion engine propulsion, and capable to do generator assistant (GA) launch for both forward and reverse. The states of the clutches C0, C1, C2, C3, B1 and B2 for all operation modes of this embodiment are summarized in the table shown in FIG. 18 .

FIG. 6 shows a sixth embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of three planetary gear sets. The first planetary gear set 10 is a simple planetary gear set, and has three elements labeled 11, 12 and 13. The second planetary gear set 20 is a simple planetary gear set, and has three elements labeled 21, 22 and 23. The third planetary gear set 50 is a simple planetary gear set, and has three elements labeled 51, 52 and 53. Elements 13 and 23 are connected with a fixed connection, and elements 21 and 53 are connected with another fixed connection, therefore there are total of two fixed connections deployed between neighboring planetary gear sets. The clutch C1 establishes a clutch connection between the element 11 and element 22. The clutch C2 establishes a clutch connection between element 23 and element 51. The clutch C3 establishes a clutch connection between element 12 and element 22. The clutch B1 establishes a clutch connection between element 11 and ground 31. The clutch B2 establishes a clutch connection between element 51 and ground 31. The clutch C0 establishes a clutch connection between element 12 and the internal combustion engine 41. The electric machine 42 is coupled with element 11, therefore the electric machine 42 is coupled with element 11 as well as with the grounding clutch B1 and connection clutch C1. The element 52 is coupled with the output shaft 43. The operation modes and vehicle operation methods of this embodiment are as same as what are described for the first embodiment of FIG. 1 , except that this embodiment has more transfer ratio for both electric machine propulsion and internal combustion engine propulsion, and capable to do generator assistant (GA) launch for both forward and reverse. The states of the clutches C0, C1, C2, C3, B1 and B2 for all operation modes of this embodiment are summarized in the table shown in FIG. 18 .

FIG. 7 shows a seventh embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of three planetary gear sets. The first planetary gear set 10 is a simple planetary gear set, and has three elements labeled 11, 12 and 13. The second planetary gear set 20 is a simple planetary gear set, and has three elements labeled 21, 22 and 23. The third planetary gear set 50 is a compound (double-pinion gear) planetary gear set, and has three elements labeled 51, 52 and 53. Elements 11 and 23 are connected with a fixed connection, and elements 21 and 53 are connected with another fixed connection, therefore there are total of two fixed connections deployed between neighboring planetary gear sets. The clutch C1 establishes a clutch connection between the element 13 and element 22. The clutch C2 establishes a clutch connection between element 23 and element 52. The clutch C3 establishes a clutch connection between element 12 and element 22. The clutch B1 establishes a clutch connection between element 13 and ground 31. The clutch B2 establishes a clutch connection between element 52 and ground 31. The clutch C0 establishes a clutch connection between element 12 and the internal combustion engine 41. The electric machine 42 is coupled with element 13, therefore the electric machine 42 is coupled with element 13 as well as with the grounding clutch B1 and connection clutch C1. The element 51 is coupled with the output shaft 43. The operation modes and vehicle operation methods of this embodiment are as same as what are described for the first embodiment of FIG. 1 , except that this embodiment has more transfer ratio for both electric machine propulsion and internal combustion engine propulsion, and capable to do generator assistant (GA) launch for both forward and reverse. The states of the clutches C0, C1, C2, C3, B1 and B2 for all operation modes of this embodiment are summarized in the table shown in FIG. 18 .

FIG. 8 shows an eighth embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of three planetary gear sets. The first planetary gear set 10 is a simple planetary gear set, and has three elements labeled 11, 12 and 13. The second planetary gear set 20 is a simple planetary gear set, and has three elements labeled 21, 22 and 23. The third planetary gear set 50 is a simple planetary gear set, and has three elements labeled 51, 52 and 53. Elements 11 and 23 are connected with a fixed connection, and elements 21 and 51 are connected with another fixed connection, therefore there are total of two fixed connections deployed between neighboring planetary gear sets. The clutch C1 establishes a clutch connection between the element 13 and element 22. The clutch C2 establishes a clutch connection between element 23 and element 53. The clutch C3 establishes a clutch connection between element 12 and element 22. The clutch B1 establishes a clutch connection between element 13 and ground 31. The clutch B2 establishes a clutch connection between element 53 and ground 31. The clutch C0 establishes a clutch connection between element 12 and the internal combustion engine 41. The electric machine 42 is coupled with element 13, therefore the electric machine 42 is coupled with element 13 as well as with the grounding clutch B1 and connection clutch C1. The element 52 is coupled with the output shaft 43. The operation modes and vehicle operation methods of this embodiment are as same as what are described for the first embodiment of FIG. 1 , except that this embodiment has more transfer ratio for both electric machine propulsion and internal combustion engine propulsion, and capable to do generator assistant (GA) launch for both forward and reverse. The states of the clutches C0, C1, C2, C3, B1 and B2 for all operation modes of this embodiment are summarized in the table shown in FIG. 18 .

FIG. 9 shows a nineth embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of four planetary gear sets. The first planetary gear set 10 is a simple planetary gear set, and has three elements labeled 11, 12 and 13. The second planetary gear set 20 is a simple planetary gear set, and has three elements labeled 21, 22 and 23. The third planetary gear set 50 is a simple planetary gear set, and has three elements labeled 51, 52 and 53. The forth planetary gear set 60 is a simple planetary gear set, and has three elements labeled 61, 62 and 63. Elements 11 and 23 are connected with a fixed connection, elements 22 and 51 are connected with another fixed connection, elements 53 and 61 are connected with another fixed connection, and elements 63 and 12 are connected with another fixed connection, therefore there are total of four fixed connections deployed between neighboring planetary gear sets. The clutch C1 establishes a clutch connection between the element 13 and element 22. The clutch C2 establishes a clutch connection between element 23 and element 52. The clutch C3 establishes a clutch connection between element 52 and element 63. The clutch B1 establishes a clutch connection between element 21 and ground 31. The clutch B2 establishes a clutch connection between element 61 and ground 31. The clutch C0 establishes a clutch connection between element 13 and the internal combustion engine 41. The electric machine 42 is coupled with element 21; therefore, the electric machine 42 is coupled with element 21 as well as with the grounding clutch B1. The element 62 is coupled with the output shaft 43. The operation modes and vehicle operation methods of this embodiment are as same as what are described for the first embodiment of FIG. 1 , except that this embodiment has more transfer ratio for both electric machine propulsion and internal combustion engine propulsion, and capable to do generator assistant (GA) launch for both forward and reverse. The states of the clutches C0, C1, C2, C3, B1 and B2 for all operation modes of this embodiment are summarized in the table shown in FIG. 19 .

FIG. 10 shows a tenth embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of four planetary gear sets. The first planetary gear set 10 is a simple planetary gear set, and has three elements labeled 11, 12 and 13. The second planetary gear set 20 is a simple planetary gear set, and has three elements labeled 21, 22 and 23. The third planetary gear set 50 is a simple planetary gear set, and has three elements labeled 51, 52 and 53. The forth planetary gear set 60 is a simple planetary gear set, and has three elements labeled 61, 62 and 63. Elements 13 and 23 are connected with a fixed connection, elements 22 and 51 are connected with another fixed connection, elements 53 and 61 are connected with another fixed connection, and elements 63 and 12 are connected with another fixed connection, therefore there are total of four fixed connections deployed between neighboring planetary gear sets. The clutch C1 establishes a clutch connection between the element 11 and element 22. The clutch C2 establishes a clutch connection between element 23 and element 52. The clutch C3 establishes a clutch connection between element 52 and element 63. The clutch B1 establishes a clutch connection between element 21 and ground 31. The clutch B2 establishes a clutch connection between element 61 and ground 31. The clutch C0 establishes a clutch connection between element 11 and the internal combustion engine 41. The electric machine 42 is coupled with element 21; therefore, the electric machine 42 is coupled with element 21 as well as with the grounding clutch B1. The element 62 is coupled with the output shaft 43. The operation modes and vehicle operation methods of this embodiment are as same as what are described for the first embodiment of FIG. 1 , except that this embodiment has more transfer ratio for both electric machine propulsion and internal combustion engine propulsion, and capable to do generator assistant (GA) launch for both forward and reverse. The states of the clutches C0, C1, C2, C3, B1 and B2 for all operation modes of this embodiment are summarized in the table shown in FIG. 19 .

FIG. 11 shows an eleventh embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of four planetary gear sets. The first planetary gear set 10 is a simple planetary gear set, and has three elements labeled 11, 12 and 13. The second planetary gear set 20 is a simple planetary gear set, and has three elements labeled 21, 22 and 23. The third planetary gear set 50 is a simple planetary gear set, and has three elements labeled 51, 52 and 53. The forth planetary gear set 60 is a simple planetary gear set, and has three elements labeled 61, 62 and 63. Elements 11 and 23 are connected with a fixed connection, elements 22 and 51 are connected with another fixed connection, elements 53 and 62 are connected with another fixed connection, and elements 63 and 12 are connected with another fixed connection, therefore there are total of four fixed connections deployed between neighboring planetary gear sets. The clutch C1 establishes a clutch connection between the element 13 and element 22. The clutch C2 establishes a clutch connection between element 23 and element 52. The clutch C3 establishes a clutch connection between element 52 and element 63. The clutch B1 establishes a clutch connection between element 21 and ground 31. The clutch B2 establishes a clutch connection between element 61 and ground 31. The clutch C0 establishes a clutch connection between element 13 and the internal combustion engine 41. The electric machine 42 is coupled with element 21; therefore, the electric machine 42 is coupled with element 21 as well as with the grounding clutch B 1. The element 62 is coupled with the output shaft 43 as well. The operation modes and vehicle operation methods of this embodiment are as same as what are described for the first embodiment of FIG. 1 , except that this embodiment has more transfer ratio for both electric machine propulsion and internal combustion engine propulsion, and capable to do generator assistant (GA) launch for both forward and reverse. The states of the clutches C0, C1, C2, C3, B1 and B2 for all operation modes of this embodiment are summarized in the table shown in FIG. 19 .

FIG. 12 shows a twelfth embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of four planetary gear sets. The first planetary gear set 10 is a simple planetary gear set, and has three elements labeled 11, 12 and 13. The second planetary gear set 20 is a simple planetary gear set, and has three elements labeled 21, 22 and 23. The third planetary gear set 50 is a simple planetary gear set, and has three elements labeled 51, 52 and 53. The forth planetary gear set 60 is a simple planetary gear set, and has three elements labeled 61, 62 and 63. Elements 13 and 23 are connected with a fixed connection, elements 22 and 51 are connected with another fixed connection, elements 53 and 62 are connected with another fixed connection, and elements 63 and 12 are connected with another fixed connection, therefore there are total of four fixed connections deployed between neighboring planetary gear sets. The clutch C1 establishes a clutch connection between the element 11 and element 22. The clutch C2 establishes a clutch connection between element 23 and element 52. The clutch C3 establishes a clutch connection between element 52 and element 63. The clutch B1 establishes a clutch connection between element 21 and ground 31. The clutch B2 establishes a clutch connection between element 61 and ground 31. The clutch C0 establishes a clutch connection between element 11 and the internal combustion engine 41. The electric machine 42 is coupled with element 21; therefore, the electric machine 42 is coupled with element 21 as well as with the grounding clutch B 1. The element 62 is coupled with the output shaft 43. The operation modes and vehicle operation methods of this embodiment are as same as what are described for the first embodiment of FIG. 1 , except that this embodiment has more transfer ratio for both electric machine propulsion and internal combustion engine propulsion, and capable to do generator assistant (GA) launch for both forward and reverse. The states of the clutches C0, C1, C2, C3, B1 and B2 for all operation modes of this embodiment are summarized in the table shown in FIG. 19 .

FIG. 13 shows a thirteenth embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of four planetary gear sets. The first planetary gear set 10 is a simple planetary gear set, and has three elements labeled 11, 12 and 13. The second planetary gear set 20 is a simple planetary gear set, and has three elements labeled 21, 22 and 23. The third planetary gear set 50 is a compound (double-pinion gear) planetary gear set, and has three elements labeled 51, 52 and 53. The forth planetary gear set 60 is a simple planetary gear set, and has three elements labeled 61, 62 and 63. Elements 13 and 23 are connected with a fixed connection, elements 21 and 53 are connected with another fixed connection, elements 51 and 62 are connected with another fixed connection, and elements 61 and 12 are connected with another fixed connection, therefore there are total of four fixed connections deployed between neighboring planetary gear sets. The clutch C1 establishes a clutch connection between the element 22 and element 63. The clutch C2 establishes a clutch connection between element 52 and element 63. The clutch C3 establishes a clutch connection between element 52 and element 61. The clutch B1 establishes a clutch connection between element 13 and ground 31. The clutch B2 establishes a clutch connection between element 11 and ground 31. The clutch C0 establishes a clutch connection between element 22 and the internal combustion engine 41. The electric machine 42 is coupled with element 13; therefore, the electric machine 42 is coupled with element 13 as well as with the grounding clutch B1. The element 62 is coupled with the output shaft 43. The operation modes and vehicle operation methods of this embodiment are as same as what are described for the first embodiment of FIG. 1 , except that this embodiment has more transfer ratio for both electric machine propulsion and internal combustion engine propulsion, and capable to do generator assistant (GA) launch for both forward and reverse. The states of the clutches C0, C1, C2, C3, B1 and B2 for all operation modes of this embodiment are summarized in the table shown in FIG. 20 .

FIG. 14 shows a fourteenth embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of four planetary gear sets. The first planetary gear set 10 is a simple planetary gear set, and has three elements labeled 11, 12 and 13. The second planetary gear set 20 is a simple planetary gear set, and has three elements labeled 21, 22 and 23. The third planetary gear set 50 is a simple planetary gear set, and has three elements labeled 51, 52 and 53. The forth planetary gear set 60 is a compound (double-pinion gear) planetary gear set, and has three elements labeled 61, 62 and 63. Elements 13 and 23 are connected with a fixed connection, elements 21 and 53 are connected with another fixed connection, elements 52 and 61 are connected with another fixed connection, and elements 62 and 12 are connected with another fixed connection, therefore there are total of four fixed connections deployed between neighboring planetary gear sets. The clutch C1 establishes a clutch connection between the element 22 and element 63. The clutch C2 establishes a clutch connection between element 51 and element 63. The clutch C3 establishes a clutch connection between element 51 and element 62. The clutch B1 establishes a clutch connection between element 13 and ground 31. The clutch B2 establishes a clutch connection between element 11 and ground 31. The clutch C0 establishes a clutch connection between element 22 and the internal combustion engine 41. The electric machine 42 is coupled with element 13; therefore, the electric machine 42 is coupled with element 13 as well as with the grounding clutch B1. The element 61 is coupled with the output shaft 43. The operation modes and vehicle operation methods of this embodiment are as same as what are described for the first embodiment of FIG. 1 , except that this embodiment has more transfer ratio for both electric machine propulsion and internal combustion engine propulsion, and capable to do generator assistant (GA) launch for both forward and reverse. The states of the clutches C0, C1, C2, C3, B1 and B2 for all operation modes of this embodiment are summarized in the table shown in FIG. 20 .

FIG. 15 shows a fifteenth embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of four planetary gear sets. The first planetary gear set 10 is a compound (double-pinion gear) planetary gear set, and has three elements labeled 11, 12 and 13. The second planetary gear set 20 is a simple planetary gear set, and has three elements labeled 21, 22 and 23. The third planetary gear set 50 is a compound (double-pinion gear) planetary gear set, and has three elements labeled 51, 52 and 53. The forth planetary gear set 60 is a simple planetary gear set, and has three elements labeled 61, 62 and 63. Elements 13 and 23 are connected with a fixed connection, elements 21 and 53 are connected with another fixed connection, elements 51 and 62 are connected with another fixed connection, and elements 61 and 11 are connected with another fixed connection, therefore there are total of four fixed connections deployed between neighboring planetary gear sets. The clutch C1 establishes a clutch connection between the element 22 and element 63. The clutch C2 establishes a clutch connection between element 52 and element 63. The clutch C3 establishes a clutch connection between element 52 and element 61. The clutch B1 establishes a clutch connection between element 13 and ground 31. The clutch B2 establishes a clutch connection between element 12 and ground 31. The clutch C0 establishes a clutch connection between element 22 and the internal combustion engine 41. The electric machine 42 is coupled with element 13; therefore, the electric machine 42 is coupled with element 13 as well as with the grounding clutch B1. The element 62 is coupled with the output shaft 43. The operation modes and vehicle operation methods of this embodiment are as same as what are described for the first embodiment of FIG. 1 , except that this embodiment has more transfer ratio for both electric machine propulsion and internal combustion engine propulsion, and capable to do generator assistant (GA) launch for both forward and reverse. The states of the clutches C0, C1, C2, C3, B1 and B2 for all operation modes of this embodiment are summarized in the table shown in FIG. 20 .

FIG. 16 shows a sixteenth embodiment of the plug-in hybrid powertrain system which includes an internal combustion engine 41, an electric machine 42 and an output shaft 43. The power transfer system of this plug-in hybrid powertrain system consists of four planetary gear sets. The first planetary gear set 10 is a compound (double-pinion gear) planetary gear set, and has three elements labeled 11, 12 and 13. The second planetary gear set 20 is a simple planetary gear set, and has three elements labeled 21, 22 and 23. The third planetary gear set 50 is a simple planetary gear set, and has three elements labeled 51, 52 and 53. The forth planetary gear set 60 is a compound (double-pinion gear) planetary gear set, and has three elements labeled 61, 62 and 63. Elements 13 and 23 are connected with a fixed connection, elements 21 and 53 are connected with another fixed connection, elements 52 and 61 are connected with another fixed connection, and elements 62 and 11 are connected with another fixed connection, therefore there are total of four fixed connections deployed between neighboring planetary gear sets. The clutch C1 establishes a clutch connection between the element 22 and element 63. The clutch C2 establishes a clutch connection between element 51 and element 63. The clutch C3 establishes a clutch connection between element 51 and element 62. The clutch B1 establishes a clutch connection between element 13 and ground 31. The clutch B2 establishes a clutch connection between element 12 and ground 31. The clutch C0 establishes a clutch connection between element 22 and the internal combustion engine 41. The electric machine 42 is coupled with element 13; therefore, the electric machine 42 is coupled with element 13 as well as with the grounding clutch B1. The element 61 is coupled with the output shaft 43. The operation modes and vehicle operation methods of this embodiment are as same as what are described for the first embodiment of FIG. 1 , except that this embodiment has more transfer ratio for both electric machine propulsion and internal combustion engine propulsion, and capable to do generator assistant (GA) launch for both forward and reverse. The states of the clutches C0, C1, C2, C3, B1 and B2 for all operation modes of this embodiment are summarized in the table shown in FIG. 20 . 

The invention claimed is:
 1. A plug-in hybrid powertrain comprising: an internal combustion engine member; an electric machine member; an output member; an ground member; multiple planetary gear sets, each has a first element, a second element and a third element; a number of fixed connections deployed between those members and elements of planetary gear sets; a number of selectively engageable clutch mechanisms deployed between those members and elements of planetary gear sets to selectively connect them to achieve multiple operation modes including multiple torque transfer ratio from electric machine to output member, multiple torque transfer ratios from internal combustion engine to output member, generator assistant launch modes for forward and reverse in the internal combustion engine based vehicle launch operations, and engine cranking mode.
 2. The plug-in hybrid powertrain of claim 1, wherein or use four planetary gear sets and five clutches (do not include engine disconnect clutch) and achieves nine torque transfer ratios from internal combustion engine to output member, four torque transfer ratio from electric machine to output member, generator assistant launch modes for forward and reverse in the internal combustion engine based vehicle launch operations and engine cranking mode; the plug-in hybrid powertrain with four planetary gear sets and five clutches being able to provide those transfer ratios and operation modes is achieved by the altogether following connection configuration principles for each planetary gear set; if those connection configuration principles are followed the same number of transfer ratios and operation modes can be always obtained; The connection and connections stated below for each element are the only and all connection and connections that element must have: the connection configuration principle for the first planetary gear set: one element of this first planetary gear set has a clutch connection with ground; another element of this first planetary gear set has a fix connection with an element of the fourth planetary gear set; and another element of this first planetary gear set has a fixed connection with an element of the second planetary gear set, a clutch connection with ground and another fixed connection with electric machine; the connection configuration principle for the second planetary gear set: one element of this second planetary gear set has a fixed connection with an element of the third planetary gear set; another element of this second planetary gear set has a clutch connection with an element of the fourth planetary gear set and a clutch connection with internal combustion engine (this clutch is the engine disconnect clutch); and another element of this second planetary gear set has a fixed connection with an element of the first planetary gear set; the connection configuration principle for the third planetary gear set: one element of this third planetary gear set has a fixed connection with an element of fourth planetary gear set; another element of this third planetary gear set has two clutch connections with another two elements of the fourth planetary gear set respectively; and another element of this third planetary gear set has a fixed connection with an element of the second planetary gear set; the connection configuration principle for the fourth planetary set: one element of this fourth planetary gear set has a fixed connection with an element of the first planetary gear set and a clutch connection with an element of the third planetary gear set; another element of this fourth planetary gear set has a fixed connection with an element of the third planetary gear set and another fixed connection with output member; and another element of this fourth planetary gear set has a clutch connection with an element of second planetary gear set and another clutch connection with an element of the third planetary gear set.
 3. The plug-in hybrid powertrain of claim 1, wherein or use three planetary gear sets and five clutches (do not include engine disconnect clutch) and achieves seven torque transfer ratios from internal combustion engine to output member, four torque transfer ratio from electric machine to output member, generator assistant launch modes for forward and reverse in the internal combustion engine based vehicle launch operations and engine cranking mode; the plug-in hybrid powertrain with three planetary gear sets and five clutches being able to provide those transfer ratios and operation modes is achieved by the altogether following connection configurations principles for each planetary gear set; if those connection configuration principles are followed the same number of transfer ratios and operation modes can be always obtained. The connection and connections stated below for each element are the only and all connection and connections that element must have: the connection configuration principle for the first planetary gear set: one element of this first planetary gear set has a fixed connection with an element of the second planetary gear set; another element of this first planetary gear set has a clutch connection with an element of the second planetary gear set and another clutch connection with the internal combustion engine (this clutch is the engine disconnect clutch); and another element of this first planetary gear set has a fixed connection with the electric machine, and a clutch connection with ground, and another clutch connection with an element of the second planetary gear set; the connection configuration principle for the second planetary gear set: one element of this second planetary gear set has a fixed connection with an element of the third planetary gear set; another element of this second planetary gear set has two clutch connections with two elements (other than the element with fixed connection with the second planetary gear set) of the first planetary gear set respectively; and another element of this second planetary gear set has a fixed connection with an element of the first planetary gear set and a clutch connection with an element of the third planetary gear set; the connection configuration principle for the third planetary gear set: one element of this third planetary gear set has a fixed connection with the output member; another element of this third planetary gear set has a clutch connection with an element of second planetary gear set and another clutch connection with ground; and another element of this third planetary gear set has a fixed connection with an element of the second planetary gear set.
 4. The plug-in hybrid powertrain of claim 1, wherein or use two planetary gear sets and five clutches (do not include engine disconnect clutch) and achieves four torque transfer ratios from internal combustion engine to output member, four torque transfer ratios from electric machine to output member, generator assistant launch modes for forward in the internal combustion engine based vehicle launch operations and engine cranking mode; the plug-in hybrid powertrain with two planetary gear sets and five clutches being able to provide those transfer ratios and operation modes is achieved by the altogether following connection configurations principles for each planetary gear set; if those connection configuration principles are followed the same number of transfer ratios and operation modes can be always obtained. The connection and connections stated below for each element are the only and all connection and connections that element must have: the connection configuration principle for the first planetary gear set: one element of this first planetary gear set has a fixed connection with an element of the second planetary gear set and another fixed connection with the output member; another element of this first planetary gear set has three clutch connections, first clutch connection with an elements of the second planetary gear set other than the one with fixed connection with the first planetary gear set, second clutch connection with another elements of the second planetary gear set other than the one with fixed connection with the first planetary gear set, third clutch connection with the internal combustion engine (this clutch is the engine disconnect clutch); and another element of this first planetary gear set has a clutch connection with an element of the second planetary gear set and a fixed connection with the electrical machine; the connection configuration principle for the second planetary gear set: one element of this second planetary gear set has a fixed connection with an element of the first planetary gear set; another element of this second planetary gear set has three clutch connections, first clutch connection with an elements of the first planetary gear set other than the one with fixed connection with the second planetary gear set, second clutch connection with another elements of the first planetary gear set other than the one with fixed connection with the second planetary gear set, third clutch connection with the ground; and another element of this second planetary gear set has a clutch connection with an element of the first planetary gear set and another clutch connection with the ground.
 5. The plug-in hybrid powertrain of claim 1, wherein or use four planetary gear sets and five clutches (do not include engine disconnect clutch) and achieves nine torque transfer ratios from internal combustion engine to output member, four torque transfer ratio from electric machine to output member, generator assistant launch modes for forward and reverse in the internal combustion engine based vehicle launch operations and engine cranking mode; the plug-in hybrid powertrain with four planetary gear sets and five clutches being able to provide those transfer ratios and operation modes is achieved by the altogether following connection configurations principles for each planetary gear set; if those connection configuration principles are followed the same number of transfer ratios and operation modes can be always obtained. The connection and connections stated below for each element are the only and all connection and connections that element must have: the connection configuration principle for the first planetary gear set: one element of this first planetary gear set has a fixed connection with an element of second planetary gear set; another element of this first planetary gear set has a fixed connection with an element of the fourth planetary gear set; and another element of this first planetary gear set has a clutch connection with an element of the second planetary gear set, and another clutch connection with the internal combustion engine (this clutch is the engine disconnect clutch); the connection configuration principle for the second planetary gear set: one element of this second planetary gear set has a fixed connection with the electric machine and a clutch connection with ground; another element of this second planetary gear set has a fixed connection with an element of the third planetary gear and a clutch connection with an element of the first planetary gear set; and another element of this second planetary gear set has a fixed connection with an element of the first planetary gear set and a clutch connection with an element of third planetary gear set; the connection configuration principle for the third planetary gear set: one element of this third planetary gear set has a fixed connection with an element of second planetary gear set; another element of this third planetary gear set has a clutch connection with an element of the second planetary gear set and another clutch connection with an element of fourth planetary gear set; and another element of this third planetary gear set has a fixed connection with an element of the fourth planetary gear set and a clutch connection with ground; the connection configuration principle for the fourth planetary set: one element of this fourth planetary gear set has a fixed connection with an element of the third planetary gear set and a clutch connection with the ground; another element of this fourth planetary gear set has a fixed connection with the output member; and another element of this fourth planetary gear set has a clutch connection with an element of third planetary gear set and a fixed connection with an element of the first planetary gear set. 